Tonegod's Wicked Switch Layout

[Fael]

I recently came across Tonegod's switching article (http://www.thetonegod.com/tech/switches/switches.html) and I am very interested in building either the "Wicked Switch: Momentary w/ NAND Gates" or the "Wicked Switch: Momentary w/ Flip-Flop (NAND)."

The problem is... well, I'm an economist. Not an electrical engineer.

I opened a thread some days ago asking for info on latching relay based true bypass but electronic switching seems: 1.- cheaper; 2.- more reliable; and 3.- easier.

However, I do not understand some aspects that I know some of you guys will be able to clarify for me.

1.- R.G. Keen has said that this is, technically, not true bypass. However, I've also read that the difference between real true bypass and electronic switching is minimal. Is this true?

Now let's go to the technical questions:

2.- The figures that look like this: are part of the NAND IC? I plan on using the 4093 IC.

From a datasheet I obtained (www.floka.com/cmos/pdf/4093.pdf), I understand that there are four figures like that one on the 4093 IC.

Does that mean that, for the Momentary w/ NAND Gates switch, there is only one 4093 IC?

Is this layout right?


3.- What should the value on the resistor labeled as "?" on the previous picture be?

4.- What does "Vs" mean?

5.- Where do pin 7 (V_ss) and pin 14 (V_dd) on the 4066 IC go to? (GND?)

6.- If a part of an IC is not illustrated (e.g, half of the 4093 IC on the Momentary w/ Flip-Flop (NAND)) does that mean that the pins are simply not connected to anything? (Or are they going to GND?)

I emphasized my questions to help you focus on my inquiries.

Thanks in advance to anyone willing to help me out.

[Earthscum]

I can answer a couple questions for you:

At a glance, layout looks correct.

4: VS is your Source Voltage. This leads to :

5: Vdd, Drain Voltage, is V+ (think fets... drain is where electrons dump(+), source is where it picks up the electrons(-)), and Vss, Source Voltage, is your Ground connection. These are your power connections.

6: generally, you tie any unused sections' inputs to ground to keep it from oscillating. This holds the output in a "high" or "low" state, and the output can be left unconnected to anything.

[Fael]

Thank you very much, Earthscum.

If I understood correctly, then, Vs and Vss go to ground and Vdd goes to V+.

Now, only the missing value for the resistor after the LED is bugging me. I guess I could try different values but I don't even know where to start. Plus the goal of the project I am trying to complete is building a high quality guitar pedal the cheapest way possible.

Also, another question arose this afternoon: is there any advantage in using a flip-flop inverter (4013 IC) over not using it? (i.e, is there any advantage in using the "Wicked Switch: Momentary w/ Flip-Flop (NAND)" over the "Wicked Switch: Momentary w/ NAND Gates"?)

[slacker]

If I understood correctly, then, Vs and Vss go to ground and Vdd goes to V+.

VS goes to V+ not ground. Generally the anode of the the LED will face the supply voltage and in this case the the anode is towards VS. The circuit works in the reverse of what you might expect, when the output of the NAND gate is high the LED is off and when the output is low it's on.

Now, only the missing value for the resistor after the LED is bugging me.

This will depend on a few things, mostly what sort of LED you use and how bright you want it to be. If you use a normal LED then values of between 1k - 10k are a good place to start, if you use "super bright" LEDs then you can go up to about 50k and get a similar brightness to a normal LED.

Also, another question arose this afternoon: is there any advantage in using a flip-flop inverter (4013 IC) over not using it?

I don't think there's any technical advantage to using the 4013, from a practical point of view if you use that you also need another IC to provide the inverter or NAND gates, these aren't part of the 4013. So to me that makes the NAND version better as that only requires 1 IC.

[Fael]

If I understood correctly, then, Vs and Vss go to ground and Vdd goes to V+.

VS goes to V+ not ground. Generally the anode of the the LED will face the supply voltage and in this case the the anode is towards VS. The circuit works in the reverse of what you might expect, when the output of the NAND gate is high the LED is off and when the output is low it's on.

Now, only the missing value for the resistor after the LED is bugging me.

This will depend on a few things, mostly what sort of LED you use and how bright you want it to be. If you use a normal LED then values of between 1k - 10k are a good place to start, if you use "super bright" LEDs then you can go up to about 50k and get a similar brightness to a normal LED.

Also, another question arose this afternoon: is there any advantage in using a flip-flop inverter (4013 IC) over not using it?

I don't think there's any technical advantage to using the 4013, from a practical point of view if you use that you also need another IC to provide the inverter or NAND gates, these aren't part of the 4013. So to me that makes the NAND version better as that only requires 1 IC.

That is a little weird. I thought that VS (Voltage Source) would go to the same place Vss (Voltage Source, Source) would go to.

Anyway, thank you very very very much. I think I am ready to try this bypass on a real pedal.

My gratitude towards this forum is matched only by the wisdom possessed by its knowledgeable members.

[Earthscum]

It used to screw with me, too. Vs is Source Voltage, and Vss is Voltage Source Source. I had to just google it a couple times to remember. R.G. may know why they do that... just remember how screwed up things are in electronics... PNP collector actually DOES collect electrons, and emits them through the emitter. The NPN is opposite... dunno why. Fets are labeled correctly.... at least n-channel fets are.

[Fael]

I found this PCB layout on Tonegod's site:


And I made this perfboard design:


The resistors are different sizes because it is pretty easy to accommodate them on perfboard.

If someone could check for errors, that would be awesome. I hope this is helpful to someone else too.

[Earthscum]

Aargh! I was looking all over for that yesterday! I breadboarded it just for the heck of it (and to see if my momentaries were gonna play nice with it). Was drawing up a couple layouts, but none were working out right. I even looked on TG's site... I knew SOMEONE had to have done a layout.  

Your layout is correct to his, and his seems to be correct. Good job 

I didn't think to put the IC's into a T... probably where I hit my roadblocks. I just didn't want jumpers or wires in the middle of the board, ya know what I mean? Wish I could get DIYLC to work... would be much easier, but good ol' pencil and grid paper works fine for me!

[diydave]

This guy also has some interesting view's on electronic switching.

http://members.shaw.ca/roma/switching.html

He describes switching with cd4016, cd4066 and cd4053, and provides graphical documentation as well.

[Pigyboy]

This is interesting too
http://www.muzique.com/schem/bypass.htm
I bought two and just ordered the relays to try them out.
I will start a thread when I have time to work on them

[Fael]

This is interesting too
http://www.muzique.com/schem/bypass.htm
I bought two and just ordered the relays to try them out.
I will start a thread when I have time to work on them

I did see that... but my unique goal on this project is achieving the lowest cost possible. Moreover, relays are not only more expensive, they're prone to break down too (although it should take like a million, or more, switches to break 'em down). Plus, being a mechanical solution, the undesirable "pop" you hear when switching may be more audible (NOTE: I may be pulling this outta my ass but I think I read that somewhere...)

[MGW]

Hey guys, new here and I've been hovering for a bit.  I rather enjoy tinkering with this stuff, but this switching thing is quite new to me.  I'm curious if either of you (Earthscum or Fael)  has tried the bypass in an actual pedal and what was the result.   I was looking at the switch layout for the perfboard above, and I'm curious as to why the cathode it on the V+ and not the anode.  Sorry if this is a completely stupid question.  Also, Fael, I found the same documentation, and I am curious how the value of the resistor connecting pins 1 and 5 on the 4093 was determined and why you elected to use 10k on the other instead of the 100K that the layout spec'd.  

I'm going to try my hand at the non momentary version as I the only switch I have is a toggle.  

Here's a perf layout...I piddled around with Fael's.  Thanks for the head start.

[MGW]

Well...here's the build report.  The switch works great.  I bought enough parts to make a few more.  I'm pretty jazzed.  There is no loss of output or tone on bypass. 

[jkokura]

What did you try it with?

Jacob

[diydave]

No little pops or hisses?
I've tried the this switch stuff some time ago. Even posted a schematic for a 3 switches with the cd4053 and 1 cd40106.
I've breadboarded 1 circuit, but got pops when switching and a high pitch hiss or really faint squeal. But I didn't bias the signalpath to halfway the voltage supply. And since then I haven't found much time to tinker with it.

Did you bias the signalpath? Or did you just hooked up the signal to the cd4066 without biasing?

Anyhow, glad it worked.

[MGW]

I tried it with at stratoblaster.  Works great, no popping, hissing squealing or otherwise.  I am getting a bit of clipping if I really crank on it....doesn't happen with the mechanical switch.  As to biasing the signal path, not that I know of.  Sorry, bit of a newb with most of this stuff, but please do explain...   If that has anything with why I am getting a bit of clipping, I'd be most appreciative of the help.

Thanks,
Scott   

[askwho69]

wow i've been looking for this one !! can you show some pic for the you've finished?

[Barcode80]

This is interesting too
http://www.muzique.com/schem/bypass.htm
I bought two and just ordered the relays to try them out.
I will start a thread when I have time to work on them

I did see that... but my unique goal on this project is achieving the lowest cost possible. Moreover, relays are not only more expensive, they're prone to break down too (although it should take like a million, or more, switches to break 'em down). Plus, being a mechanical solution, the undesirable "pop" you hear when switching may be more audible (NOTE: I may be pulling this outta my ass but I think I read that somewhere...)

Though being a mechanical solution can contribute to popping, that in and of itself does not pop. Maybe I'm misreading your statement, but it seems you are saying there is always a pop with mechanical switching, which is definitely not the case. At least not a pop in the audio path.

Relays also last about a million times longer than basic switches, because a regular switch has to bear the shock of the stomp, where relays aren't directly smashed with ones foot and therefore last a lot longer. And on average, they will outlast the other components on your average stompbox...

[askwho69]

By the way what resistors you'd use?

[deadastronaut]

hmmmm....so is the age of the 3pdt dead then?...anyone done it with good results?